A Performance Comparison of Color Vision Tests for Pilots ... · Arrangements test Lanthony 15 Hue Munsell 100 Hue CAD (Colour Assessment and Diagnosis) test Anomaloscope Nagel type

A Performance Comparison of

Color Vision Tests for Pilots

Requirement

M. Marechal, M. Delbarre, J. Tesson, C. Lacambre, F. Froussart-Maille

Percy Military Hospital,

Clamart, FRANCE

Introduction

Color-deficiency

9 % of men and 0.5 % of women

1.5 to 3% of military pilots candidates (Air Force)

11 to 13% of ophthalmologic incapacity

Protanomalous trichromat

Anomalous trichromats

(abnormal cone) Deuteranomalous trichromat

Protanopes

Dichromats

(absent cone) Deuteranopes

Maille M, Crepy P. Les nouvelles normes visuelles en aéronautique militaire. Médecine Aéronautique Spatiale. 1990;XXIX:261–2

Introduction

Color use in aviation

access to information : first symbol, text, or sound.

PAPI (Precision Approach Path Indicator) is the more critical

Other are less problematic :

Parking lights

Taxiways

Regulatory lights of airplanes.

Introduction

Color is more and more present in cockpits,

"glass cockpits“ : LCD screens with electronic process of many instruments

of flights, whose display is multicolored.

Colors choice : free to the manufacturer

Located in different areas of confusion according to MacAdam ellipses

Introduction - rules

In France : Decree of 27 January 2005 and follow the regulations of EASA

- pass the Ishihara 24 plate test (first 15 plates identified without error or hesitation)

- ‘normal trichromat’ at the Nagel anomaloscope

- identification without mistake or hesitation of colored lights

in Beyne lantern(presented at 5 meters for 1 second with 3 minutes of arc aperture)

- matching range is 4 scale units or less to the Nagel anomaloscope

Normal

Color vision

Color vision

Safe

Introduction - rules

In France : Decree of 27 January 2005 and follow the regulations of EASA

- pass the Ishihara 24 plate test (first 15 plates identified without error or hesitation)

- ‘normal trichromat’ at the Nagel anomaloscope

- identification without mistake or hesitation of colored lights in Beyne lantern(presented at 5 meters for 1 second with 3 minutes of arc aperture)

- matching range is 4 scale units or less to the Nagel anomaloscope

Secondary tests in other countries

In UK : Holmes-Wright lantern or CAD test

In Germany : Anomaloscope

In USA : Farnsworth and Optec lanterns or Titmus vision test

In Canada : lantern test or Farnsworth D15

In New Zeland : Farnsworth and Holmes-Wright lanterns, Farnsworth D15 or CAD

test

Normal

Color vision

Color vision

Safe

Introduction

Lanterns : no more commercialized (only Fletcher-Evans CAM lantern)

Aim of the study

To assess the abilities of 8 color vision tests

for screening, qualification and quantification of red / green

hereditary deficiency,

to improve and to adapt the current color selection protocols.

Methods

INCLUSION

Color-deficient subjects:

addressed for a failure in

reading the Ishihara plates by

- military selection center

- or Aviation Medical

Examiner.

Color vision normal subjects : healthy volunteers.

EXCLUSION

BCVA less than 6/10.

Sunglasses or tinted contact

lenses.

Ophthalmologic pathology

(evolutionary or sequelar).

Prospective study

September 2016 to May 2017

CPEMPN of Percy hospital, in Clamart (France).

Methods - color vision test

Ishihara

Beyne lantern

Fletcher lantern

Farnsworth D15

Arrangements test Lanthony 15 Hue

Munsell 100 Hue

CAD (Colour Assessment and Diagnosis) test

Anomaloscope Nagel type


Ishihara 38 plates

Out of order

at 70 cm of distance, at 45°

3 seconds for each plate

successful if the first 17 plates were viewed without error or hesitation.


Ishihara

Beyne lantern

Fletcher lantern

Farnsworth D15


Munsell 100 Hue




Beyne lantern type aviation

simple colored lights, in random order

low mesopic conditions, at 5 meters

any hesitation or false answer = an error

2 protocols without cited colors

1 s / 4’ : presentation 1 second with 4 minutes of arc aperture

1/25th s / 2 : presentation 1/25th second with 2 minutes of arc aperture

2 protocols with colors cited (red, green, blue, yellow-orange and off-white)

1 s / 3’ : presentation 1 second with 3 minutes of arc aperture

1 s / 3’ x 3 presentations (pass if no error on 2 of 3 presentation)

military

civilian


Ishihara

Beyne lantern

Fletcher lantern

Farnsworth D15


Munsell 100 Hue




Fletcher-Evans CAM lantern

two lights, vertically

6 meters

5 colors : 2 Red, 2 Green, 1 White

9 combinations

Informative phase : colors presented and cited 'red', 'green' and 'white ‘.

test phase : 0.9 minute of arc , 2 seconds

First round : pass if no error

Two more rounds if errors


Ishihara

Beyne lantern

Fletcher lantern

Farnsworth D15


Munsell 100 Hue




Arrangement tests

Farnsworth D15

▪ to classify the 16 pawns in a time of 3 minutes.

▪ successful if no confusion right (circular scheme)a straight between the pawns 7 and 15, a simple pawns inversions.

Desaturated Lanthony 15 Hue

▪ successful if less than 2 lines of confusion

Farnsworth-Munsell 100 Hue

▪ 2 minutes /box x 4

▪ axis of the deficiency

▪ severity score


Ishihara

Beyne lantern

Fletcher lantern

Farnsworth D15


Munsell 100 Hue




The CAD Test (Colour Assessment and Diagnosis)

Mesopic condition at 1.40 meter in front of the viewing screen,

3 steps

'learning mode’ : check the test understanding.

'fast screening’ : identify a large part of the healthy subjects.

‘definitive CAD’ : determine the chromatic sensitivity of the subject present for each wavelength stimuli of varying intensity.

determines the axis and severity according to a score (RG for the Red-Green axis and YB for blue-yellow axis)

Ability according to UK threshold : RG < 6 SN for protans and RG< 12 SN for deutans

Healthy subjects : score < 2 SN


Ishihara

Beyne lantern

Fletcher lanter

Farnsworth D15


Munsell 100 Hue




The anomaloscope IF2, Tomey

Rayleigh equation,

on the dominant eye in mesopic conditions

2 modes : Automatic or Manual

identifies the deficiency axis, differentiates anomalous trichromats from

dichromats, or class the subject in normal color vision

matching range severity

Safe : if matching range less than 4 units at the Nagel anomaloscope

Methods

For each test, evaluation of :

▪ Sensibility, Specificity, Positive and negative predictive values

▪ Application to aeronautic : Total number and success ratio for class 1 ability

▪ Severity assessing : ROC curves for dichromatism diagnosis

for CAD test and 100 Hue

2 groups : CVD : color vision deficient

CVN : color vision normal

Results

55 subjects

32 color vision deficient subjects (CVD). 3 were excluded (missing

results)

23 color vision normal subjects (CVN).

29 VCD 23 VCN p

23 years ± 6.09 26 ± 6.1 years p = 0.075

0 woman 9 women p = 0.015

- 11 deuteranomalous trichromats (37.9%)

- 7 protanomalous trichromats (24.1%)

- 6 protanopes (20.69%)

- 5 deuteranopes (17.24%)

Results

Detection of

color-deficiency

tests power

Se Sp PPV NPV

ISHIHARA 0.97 1.00 1.00 0.96

FARNSWORTH D15 0.58 1.00 1.00 0.64

LANTHONY HUE desaturated 0.79 1.00 1.00 0.79

MUNSELL 100 HUE 0.79 0.96 0.96 0.79

BEYNE Lantern

1s / 4' 0.79 0.96 0.96 0.79

1/25th s 2' 0.97 0.57 0.76 0.93

1s / 3' 0.76 0.96 0.96 0.76

1 s 3' x 3 series 0.69 1.00 1.00 0.72

FLETCHER Lantern 1 presentation 1.00 0.78 0.85 1.00

2 retests 0.97 1.00 1.00 0.96

CAD test 1.00 1.00 1.00 1.00

ANOMALOSCOPE Automatic 0.97 0.96 0.97 0.96

Manual 1.00 1.00 1.00 1.00

Results

Total number and success ratio for a class 1 ability for CVD

Test Deuteranomalous

trichromats Deuteranopes

Protanomalous

trichromats Protanopes

All

n = 11 in % n = 5 in % n = 7 in % n = 6 in % n=29 in %

ISHIHARA 1 9.09 0 0.00 0 0.00 0 0.00 1 3.44

FARSNWORTH D15 5 45.45 0 0.00 5 71.42 2 33.33 12 41.38

LANTHONY D15 4 36.36 0 0.00 2 28.57 0 0.00 6 20.69

MUNSELL 100HUE 3 27.27 0 0.00 2 28.57 1 16.67 6 20.69

Beyne lantern

1s / 4' 5 45.45 0 0.00 1 14.29 0 0.00 6 20.69

1/25th s / 2' 1 9.09 0 0.00 0 0.00 0 0.00 1 3.44

1s / 3' 3 27.27 1 20.00 2 28.57 1 16.67 7 24.14

1s / 3' x 3 6 50.00 0 0.00 2 28.57 1 16.67 9 31.03

Fletcher

lantern

1 present. 0 0.00 0 0.00 0 0.00 0 0.00 0 0.00

2 retests 1 9.09 0 0.00 0 0.00 0 0.00 1 3.44

CAD test 2 18.18 0 0.00 1 14.29 0 0.00 3 10.34

ANOMALOSCOPE 4 36.36 0 0.00 2 28.57 0 0.00 6 20.69

Results

Total number and success ratio for a class 1 ability for CVD

Test Deuteranomalous

trichromats Deuteranopes

Protanomalous

trichromats Protanopes

All

n = 11 in % n = 5 in % n = 7 in % n = 6 in % n=29 in %

ISHIHARA 1 9.09 0 0.00 0 0.00 0 0.00 1 3.44

FARSNWORTH D15 5 45.45 0 0.00 5 71.42 2 33.33 12 41.38

LANTHONY D15 4 36.36 0 0.00 2 28.57 0 0.00 6 20.69

MUNSELL 100HUE 3 27.27 0 0.00 2 28.57 1 16.67 6 20.69

Beyne lantern

1s / 4' 5 45.45 0 0.00 1 14.29 0 0.00 6 20.69

1/25th s / 2' 1 9.09 0 0.00 0 0.00 0 0.00 1 3.44

1s / 3' 3 27.27 1 20.00 2 28.57 1 16.67 7 24.14

1s / 3' x 3 6 50.00 0 0.00 2 28.57 1 16.67 9 31.03

Fletcher

lantern

1 present. 0 0.00 0 0.00 0 0.00 0 0.00 0 0.00

2 retests 1 9.09 0 0.00 0 0.00 0 0.00 1 3.44

CAD test 2 18.18 0 0.00 1 14.29 0 0.00 3 10.34

ANOMALOSCOPE 4 36.36 0 0.00 2 28.57 0 0.00 6 20.69

Results

CVDIshihara D15

15HUE

Lanthony.

100

HUE

BEYNE lantern FLETCHER lanternCAD

testAnomal.

1/4 1/25th 2 1/3 3 tests 1 test 2 retests

1 fail fail fail fail fail fail fail PASS fail fail fail fail

2 fail PASS PASS fail fail fail fail Fail fail fail PASS PASS

4 fail PASS PASS fail fail fail PASS PASS fail fail fail PASS

5 fail PASS fail fail fail fail fail fail fail fail fail fail


7 fail fail fail fail fail fail PASS PASS fail fail fail fail

11 fail fail fail fail fail fail PASS fail fail fail fail fail

14 fail fail fail fail PASS fail fail fail fail fail fail PASS

15 fail PASS fail fail PASS fail fail fail fail fail fail fail

16 fail fail fail fail fail fail fail PASS fail fail fail fail


20 fail PASS PASS fail fail fail fail PASS fail fail PASS fail

22 fail fail fail PASS fail fail fail fail fail fail fail fail

24 fail PASS PASS fail PASS PASS PASS PASS fail fail fail PASS

25 fail fail fail fail fail fail PASS PASS fail fail fail fail

26 fail PASS fail PASS fail fail PASS PASS fail fail fail fail

27 fail fail fail fail PASS fail fail fail fail fail fail fail

29 fail PASS fail PASS PASS fail fail fail fail fail fail PASS

30 fail PASS PASS PASS fail fail fail PASS fail PASS PASS PASS

31 fail fail PASS PASS fail fail fail fail fail fail fail fail

Results

Deficit quantification

CAD test100 Hue : difference

between achieved score and physiologic score

100 Hue : achieved score

Best cut-off:- RG > 18,5 for CAD test

- Score difference > 22

- Score > 112 for 100 Hue

AUC:- 0,98 [0,94 ; 1,01] for CAD test

- 0,65 [0,47 ; 0,83] for score

difference

- 0,69 [0,52 ; 0,86]for 100 Hue

Discussion

Walsh in 2016 , USA

65 CVD subjects and 68 CVN subjects of US Army.

Our results : similar except a better diagnostic efficiency of the CAD test.

good efficiency of the computerized tests CCT and CAD

operator-independent and randomized patterns

Test Sensitivity Specificity

CAD test 0.86 0.85 to 1.00

Farnsworth D15 0.35 1.00

FALANT 0.92 to 0.86 0.96

3 presentations 0.83 to 0.85 0.97 to 0.99

PIPIC 0.98 0.96 to 1.0

Walsh DV, Robinson J, Jurek GM, Capó-Aponte JE, Riggs DW, Temme LA. A Performance Comparison of Color Vision Tests for Military Screening. Aerosp Med Hum Perform. 2016 Apr;87(4):382–7.

Discussion

Squire et al. in 2005, UK

3 lanterns (Beyne, Spectrolux, and Holmes-Wright)

and Nagel anomaloscope.

55 CVD subjects and 24 CVN subjects.

all dichromats failed the 4 tests.

pass one secondary test : not guaranteed to pass the other tests

Tests authorized by the EASA standards : high variability and

inconsistency of their results.

Squire TJ, Rodriguez-Carmona M, Evans ADB, Barbur JL. Color vision tests for aviation: comparison of the anomaloscope and three lantern types. Aviat Space Environ Med. 2005 May;76(5):421–9.

Discussion

British CAA, 2006

117 CVD

Ability of PAPI lights recognition and CAD test results

No subject who pass CAD test failed to PAPI simulator.

(pass : RG < 6 SN for protan or RG < 12 SN for deutan)

CAD test : pass in 36.1 % of deuteranomalous trichromats

29.8% of protanomalous trichromats

In our study : only 18.2% deuteranomalous trichromats

14.3% protanomalous trichromats

Barbur JL, Rodriguez-Carmona M, Evans S, Milburn N. Minimum Colour Vision Requirements for Professionnal Flight Crew. Recommendations for a new colour vision standards. Safety Regulation Group. Civil Aviation Authority; 2009.

Discussion

Fletcher in 2005

▪ Similar to Holmes-Wright lantern : 2 lights with a 0.9 minute arc aperture. Colors used : slight differences in the CIE diagram.

▪ 9 / 71 normal trichromats : mistakes in first pass.

▪ 18 color-deficient subjects : all failed.

Fletcher-Evans CAM lantern : very sensitive. good test for clinical diagnosis, not for chromatic selection.

Birch in 2008

▪ Holmes-Wright lantern type A

▪ 125 color-deficient subjects: 10 subjects (9%) were able to pilot

Nevertheless, Fletcher lantern not comparable to the Holmes-Wright lantern (passing 9 to 30% of CVD)

- Fletcher R. The Fletcher CAM lantern colour vision test. Optom Today. 2005 Jul;(29):24–6. - Birch J. Performance of colour-deficient people on the Holmes-Wright lantern (type A): consistency of occupational colour vision standards in aviation. Ophthalmic Physiol Opt. 2008 May;28(3):253–8.

Discussion

Professional selection specificity

Candidates try to minimize their color-vision deficit / learn Ishihara consider any hesitation / mistake as failure.

testing protocol should be strictly respected and examiners must be

trained,

▪ that can be an impediment to the use of anomaloscope

▪ In some cases, automatic mode may fail to categorize the candidate.

Discussion

Test duration is to take in account in a screening context.

Ishihara album : 2 minutes

Beyne lantern : 1 mn, and Fletcher-Evans CAM lantern : 5 mn

Both test of D15 : 2 - 3 mn, 100 Hue : 15 mn

Anomaloscope with both automatic and manual mode : 20 mn

CAD test : < 5 mn if "Fast screening" is successful.

In our study, 6 CVN (26%) had “Definitive CAD” : 8 mn for

red/green (3-4 mn for blue / yellow if necessary).

Discussion

CAD test

Advantages

▪ Can’t be learn

▪ Reproducible

▪ Red / green and yellow / blue axis

▪ 16 colors

▪ Quantitative test

Lanterns

Advantages

▪ Quick

▪ Easy

▪ Less expensive

▪ Ergonomic test

Conclusion

Many tests are used for pilots ability. Their results are discordant

lanterns are no more commercialized.

CAD test and anomaloscope : most accurate in our study

Recent increase of colored signals in new generation cockpits.

Multitude of color amount.

The acceptable color-deficiency for a pilot to be safe is difficult to

determine, as well as the risk of not detected blue-yellow

deficiency.

Thank you for your

attention

Discussion

In conclusion

▪ Ishihara plates : excellent screening test for red / green deficiency.

▪ Farnsworth D15 : quick and easy but some dichromats subjects can pass this test.

▪ Lanthony 15 Hue test : ability of 20% and seems suitable for use in professional

selection.

▪ Munsell 100 Hue : too long

▪ Fletcher-Evans CAM lantern : too restrictive

▪ Beyne lantern : simple and quick to use, but some dichromats pass.

▪ Anomaloscope : qualify and quantify the deficiency

requires a strong experience of the examiner.

▪ CAD test : quantitative test , yellow/blue and red/green

thresholds used by the British CAA seem to be more restrictive

More expensive

Results

Assessment of

the axis of the color-deficiency

ANOMALOSCOPE Diagnosis ISHIHARA D15

LANTHONY

15HUE 100 HUE CAD

deutan 15 11 9 12 16

all CVD protan 9 6 12 6 13

n = 29 not defined 5 12 8 11 0

Deuteranomalous deutan 10 6 5 6 11

Trichromats protan 0 0 2 0 0

n = 11 not defined 1 5 4 5 0

deutan 5 5 4 5 5

Deuteranopes protan 0 0 0 0 0

n = 5 not defined 0 0 1 0 0

Protanomalous deutan 0 0 0 1 0

Trichromats protan 4 2 4 2 7


deutan 0 0 0 1 0

Protanopes Protan 5 4 6 4 6


Documents

A Performance Comparison of Color Vision Tests for Pilots ... · Arrangements test Lanthony 15 Hue Munsell 100 Hue CAD (Colour Assessment and Diagnosis) test Anomaloscope Nagel type